The Justice Department's decision to subpoena a New York Times reporter this week has convinced some press advocates that President Obama's team is pursuing leaks with the same fervor as the Bush administration.

"The message they are sending to everyone is, 'You leak to the media, we will get you,' " said Lucy Dalglish, executive director of the Reporters Committee for Freedom of the Press. In the wake of the Bush administration's aggressive stance toward the press, she said, "as far as I can tell there is absolutely no difference, and the Obama administration seems to be paying more attention to it. This is going to get nasty."

Kurt Wimmer, a Washington lawyer who helped win White House approval for a proposed federal shield law, called the move against Risen "disappointing" after "we had positive discussions with the Obama administration" on the need to give journalists a legal foundation for protecting their sources in most cases.

In the Risen case, Attorney General Eric Holder had to approve the subpoena under Justice Department procedures. The subpoena, disclosed Thursday by the Times, comes two weeks after the administration obtained an indictment of a former top National Security Agency official, Thomas Drake, for allegedly providing classified information to a Baltimore Sun reporter.

Law enforcement officials, who declined to be identified discussing pending investigations, said the close timing of the two cases was coincidental and that the administration is not mounting an intensified effort to crack down on leakers. "As a general matter, we have consistently said that leaks of classified information are something we take extremely seriously,'' said Matthew Miller, chief Justice spokesman, who declined further comment.

Joel Kurtzberg, Risen's lawyer, said the subpoena focuses on his reporting on covert CIA attempts to combat alleged nuclear weapons research by Iran. In one book chapter, Risen wrote that the CIA sent a Russian defector to Vienna in 2000 to provide an Iranian official with plans for a nuclear-bomb-triggering device -- one with a deliberate technical flaw -- along with a solicitation for payment. Risen depicted the operation as giving Iran valuable information.

"We will be fighting to quash the subpoena," Kurtzman said. "Jim is the highest caliber of reporter and adhered to the highest standards of his profession in writing Chapter 9 of his book. And he intends to honor the promise of confidentiality he made to the source or sources."

The Times said in a statement that Risen and his publisher, Simon and Schuster, are handling the matter because the subpoena does not involve material published by the paper. "Our view, however, is that confidential sources are vital in getting information to the public, and a subpoena issued more than four years after the book was published hardly seems to be important enough to outweigh the protection an author needs to have," the newspaper said.

Dalglish described the subpoena as "troublesome" and said defense attorneys have told her that several similar cases against alleged leakers are in the pipeline. The subpoena was first brought under Bush's last attorney general, Michael Mukasey, but the grand jury in the case expired without resolving the matter, prompting Holder's department to empanel a new grand jury. The Bush administration also launched a leak probe involving the Times story but no charges were brought.

If Risen is unable to quash the subpoena, he could face a contempt citation similar to the one that landed then-Times reporter Judith Miller in jail for 85 days during the prosecution of Lewis "Scooter" Libby, a top aide to Vice President Dick Cheney.

The White House last fall reached a compromise with key senators on drafting a shield law, a version of which has passed the House, but the measure would have limited application in national security cases. Even if the bill were law, Dalglish said, the Risen case "is a tough one for a journalist to get quashed."